Cancer History and Subjective Sleepiness in Obstructive Sleep Apnea: A Real-World Observational Study

Background/Objectives: Daytime sleepiness in obstructive sleep apnea (OSA) shows substantial variability and is not fully explained by disease severity. This study aimed to evaluate whether a history of cancer is associated with subjective daytime sleepiness independently of respiratory burden. Methods: In this observational cohort study, 402 untreated patients with OSA were included. Cancer history was defined as a documented diagnosis of malignancy prior to baseline polygraphy. Daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS). Multivariable linear and logistic regression models were used to evaluate the association between cancer history and ESS (continuous and dichotomized as >10), adjusting for age, sex, body mass index, smoking status, chronic obstructive pulmonary disease, and apnea-hypopnea index (AHI). Sensitivity analyses additionally adjusted for heart disease and nocturnal hypoxic burden. Results: Sixty-two patients (15%) had a history of cancer. OSA severity and hypoxemia indices were comparable between groups. In multivariable analysis, cancer history was independently associated with modestly lower ESS scores (B = -1.66, 95% confidence interval [CI] -2.96 to -0.37; p = 0.012) and a reduced likelihood of excessive daytime sleepiness (ESS > 10) (odds ratio [OR] = 0.25, 95% CI 0.07 to 0.85; p = 0.027). Conclusions: In this real-world cohort of untreated patients with OSA, cancer history is associated with modestly lower subjective daytime sleepiness despite comparable disease severity, supporting a potential dissociation between physiological burden and symptom perception. These findings indicate that reliance on subjective sleepiness alone may contribute to under-recognition of clinically relevant OSA in patients with a cancer history.